1. Field of the Invention
The invention in general relates to rotating machinery, and more particularly to apparatus for electrically grounding a portion of the machinery during use and which apparatus will provide information relative to various operating conditions of the machinery.
2. Description of the Prior Art:
Operation of some types of rotating machinery, such as a steam turbine, results in an electrical charge build-up on the rotor, or shaft, which is supported at spaced apart locations by bearings. The shaft actually rides on a thin film of lubricant in the bearing and accordingly is electrically insulated from ground potential. The build-up of an excessive electrical charge on the shaft can cause a discharge through the lubricant film resulting in eventual damage to the bearings.
In order to prevent such discharge, grounding devices are provided for contacting the shaft as it rotates to afford a discharge path to ground for the electrical charge build-up. During the operating life of the grounding device, a film build-up occurs thereby interrupting a continuous path to ground for the electrical charge. A voltage thereby builds up on the shaft to a certain threshold value whereby a discharge through the oil film takes place, leading to bearing damage.
The present invention provides for a system which prevents such bearing damage by preventing or minimizing any charge build-up on the shaft. In addition, the system allows for the diagnosis of different operating conditions of the turbine.